HOT: Active* forum members generally gain 5% discount at starbike.com store!
Weight Weenies
* FAQ    * Search    * Trending Topics
* Login   * Register
HOME Listings Articles FAQ Contact About




Post new topic Reply to topic  [ 15 posts ] 
Author Message
PostPosted: Wed May 07, 2014 7:51 am 
Offline

Joined: Wed Nov 30, 2005 1:35 am
Posts: 171
Hi all. I have a slight problem and I don't really know where the exact issue lies.

I have a roadbike with 39/53 on the front and have installed a new 11/28 casette on the rear. I've calculated the chain wrap capacity to be 31.

The issue I'm having is that when I adjusted the new chain by putting the front onto the 39t and the rear on the 11t (worst case scenario for chain slack) and shorten the chain to suit, I can gear down to the 53/28t but when I do, the pedals lock up. My guess is that the chain is too short to be on the 53/28.

I then added extra links to the chain so I can go 53t on the front and 28t on the rear (even though I dont ride that combo but have done so accidentally) the chain has too much slack when I go to 39t and 11t on the rear.

I haven't checked my derailleur yet but I'm pretty sure it's a short cage. From what I've read, the short cage derailleur I have will accommodate a 11/28 rear cassette (chainwrap of 33 I think)

Has anybody got any advice on what I can try next?
Thanks

Sent from my GT-I9300 using Tapatalk


Top
 Profile  
 
Posted: Wed May 07, 2014 7:51 am 


Top
  
 
PostPosted: Wed May 07, 2014 8:23 am 
Offline
Formerly known as CAADHEAD
User avatar

Joined: Sun Dec 21, 2003 8:32 pm
Posts: 1422
Location: WALES,UK
I'm running that set up with no issues as I assume many others are. Two things spring to mind, is your rear mech springing back enough? maybe the pivot bolt is a little seized up? Or trying slackening off the B-tension screw, that will allow the mech to spring back more.

_________________
Ti or dye!

The Weenie formally known as CAADHEAD


Top
 Profile  
 
PostPosted: Wed May 07, 2014 8:38 am 
Offline

Joined: Wed Nov 30, 2005 1:35 am
Posts: 171
I took the derailleur off and made sure it wasn't seized. I haven't tried backing off the B tension screw but I will try rhat and let you know how it gows. Thanks for the advice.

Sent from my GT-I9300 using Tapatalk


Top
 Profile  
 
PostPosted: Wed May 07, 2014 9:07 am 
Offline

Joined: Thu Jan 08, 2004 10:11 pm
Posts: 672
http://www.parktool.com/blog/repair-hel ... gth-sizing


Top
 Profile  
 
PostPosted: Wed May 07, 2014 11:34 am 
Offline

Joined: Wed Jul 16, 2008 10:37 am
Posts: 129
Chain length must be wrong, no other reason if the RD has a 33t capacity, in the small-small (39-11)
lower run of the chain should just be missing the RD cage like this, what RD are you running?
Image


Top
 Profile  
 
PostPosted: Wed May 07, 2014 10:34 pm 
Offline

Joined: Wed Nov 30, 2005 1:35 am
Posts: 171
Thanks for your posts guys. I tried the link provided by Oswald and all is good now.

I am running a dura ace RD. I'll take a pic tonight of the RD position when in the 39/11 and 53/28. When in the 53/28 it doesn't jam up.

Sent from my GT-I9300 using Tapatalk


Top
 Profile  
 
PostPosted: Thu May 08, 2014 11:16 am 
Offline

Joined: Wed Nov 30, 2005 1:35 am
Posts: 171
Ok. Had another look at my setup tonight. I think that the chain might still be a link too long. If anybody has their ratios the same as mine, can you please measure your chain and I can do the same. In the ratio 39/11 the chain isn't completely slack but I think it could be a tad tighter.
Image

Image

Image

Image

Sent from my GT-I9300 using Tapatalk


Top
 Profile  
 
PostPosted: Thu May 08, 2014 11:18 am 
Offline

Joined: Wed Nov 30, 2005 1:35 am
Posts: 171
Also. I can't seem to get the RD pulley away any more from the 28t with the B adjuster. It is screwed all the way in.

Sent from my GT-I9300 using Tapatalk


Top
 Profile  
 
PostPosted: Thu May 08, 2014 5:18 pm 
Offline

Joined: Wed Apr 08, 2009 7:49 pm
Posts: 44
The length of the chain isn't going to necessarily give you the answer you desire, because the chain stays will vary in length dependent on the make and size of the bike.


Top
 Profile  
 
PostPosted: Thu May 08, 2014 6:05 pm 
Offline

Joined: Thu Jan 08, 2004 10:11 pm
Posts: 672
slick1 wrote:
I tried the link provided by Oswald and all is good now.


Yep, Parktool website always comes in handy when you need to fix your bike. Whenever I have to fix something that I don't do very often, I check their site before I start working. :D


Top
 Profile  
 
PostPosted: Thu May 08, 2014 6:27 pm 
Offline
Shop Wrench
User avatar

Joined: Sat Nov 29, 2008 6:15 am
Posts: 708
the rd-7800 has a max cog size of 27t. This is obviously splitting hairs, but pair that with unknown hanger geometry; some bikes are shorter or longer then others; and that may be your problem with the pulley clearance. As far as length goes, you look right on. Another check you can do is put the bike in the 53/11 and see if the two pulleys are roughly perpindicular to the ground, if so you are good.

_________________
"Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius -- and a lot of courage -- to move in the opposite direction."


Top
 Profile  
 
PostPosted: Thu May 08, 2014 7:59 pm 
Offline

Joined: Tue Nov 11, 2003 9:47 pm
Posts: 1639
Location: Santa Cruz, California, USA
That hanger looks pretty short. Maybe try an xx-27 cassette or use an RD-7900.


Top
 Profile  
 
PostPosted: Thu May 08, 2014 11:17 pm 
Offline

Joined: Wed Nov 30, 2005 1:35 am
Posts: 171
Thanks @743power. I'll try it tonight.

I'm happy with the 11/28. I might upgrade to the 7900 RD. That will fix the problem I hope.

Sent from my GT-I9300 using Tapatalk


Top
 Profile  
 
PostPosted: Sun May 11, 2014 12:14 am 
Offline

Joined: Wed Nov 30, 2005 1:35 am
Posts: 171
Ok. I took some pics of the RD in the 53/11. The pulleys aren't directly in line. Looks like an additional link can come out.

Image

This picture is the RD position when I have selected 53/27 (worst case scenario for chain tension) with 1 less link. I did this by pulling the chain 1 link tighter when it was on the big chainring

Image


Sent from my iPad using Tapatalk


Top
 Profile  
 
Posted: Sun May 11, 2014 12:14 am 


Top
  
 
PostPosted: Tue May 13, 2014 3:27 pm 
Offline
Shop Wrench
User avatar

Joined: Sat Nov 29, 2008 6:15 am
Posts: 708
I always prefer a longer chain. Puts less stress on the derailleur. The photo you posted previously of the bike in small small is the right length. If you are in that combo and their is tension on the derailleur cage but the chain is not running the tab in between the pulleys, you are at the right length. The latest photo in big big is still OK, but I would prefer one link longer.

_________________
"Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius -- and a lot of courage -- to move in the opposite direction."


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 15 posts ] 


Who is online

Users browsing this forum: Google [Bot], jvanv8, Larry_Pang, rmerka and 55 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  

   Similar Topics   Author   Replies   Views   Last post 
There are no new unread posts for this topic. Crack in paint rear of head tube, z5.

[ Go to page: 1, 2 ]

in Road

jaup

15

1521

Sat Mar 29, 2014 12:12 pm

sugarkane View the latest post

There are no new unread posts for this topic. New cassette - chain question

in Road

jmsp

3

426

Fri May 30, 2014 11:39 am

jmsp View the latest post

There are no new unread posts for this topic. Cassette Mixing & Chain Length

in Road

Ltoddokc

14

434

Thu Jul 24, 2014 7:45 pm

FIJIGabe View the latest post

There are no new unread posts for this topic. Light weight campag 11sp chain/cassette options.

in Road

stevebax

10

332

Fri Jul 25, 2014 1:01 am

NiFTY View the latest post

There are no new unread posts for this topic. Shimano 7800 Chain, 9000 cassette, Wahoo trainer

in Road

Horacio

7

459

Thu Mar 20, 2014 3:34 am

Horacio View the latest post


It is currently Wed Jul 30, 2014 12:50 pm

All times are UTC + 1 hour




Advertising   –  FAQ   –  Contact   –  Convert   –  About

© Weight Weenies 2000-2013
hosted by starbike.com


How to get rid of these ads? Just register!


Powered by phpBB